Xenons fitted from factory come with auto leveling. AL controls what angle (up or down) the lights project at. Say you are going up a hill, AL will lower the beams to avoid blinding on-coming vehicles and vise versa. I know of a case whereby someone was in an accident and had xenons without AL and it was the other persons fault but the guy said he was blinded by the lights and the innocent guy was held liable for the accident which was frankly ridiculous. Xenons fitted from factory also have to have washers to by law. I have heard in Europe all the above has to be strictly adhered to.